Mortgage Stress Test Calculator
When your fixed-rate mortgage ends, you'll move to a new deal – potentially at a much higher rate. A stress test shows whether you could still afford your payments if rates rise.
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Many homeowners focus only on their current payment without considering what happens when their fix expires. A £200,000 mortgage at 2% costs around £850 per month, but at 6% that jumps to £1,288 – a 50% increase.
Running a stress test helps you plan ahead and build a buffer. Enter your mortgage details below to see how your payments would change at different interest rates.
Your Mortgage Details
Include loans, credit cards, childcare, etc.
Lenders typically stress test at 3% above their standard variable rate
Stress Test Results
Low Risk - You should comfortably afford your mortgage even if rates rise significantly.
Current Payment
£0
per month
Stressed Payment
£0
per month
Payment Increase
+£0
extra per month at 7.0% rate
Income Ratio Guidelines
- Below 35%: Comfortable affordability
- 35-50%: Budget may be stretched
- Above 50%: High affordability risk
This calculator provides estimates only. Actual affordability depends on individual circumstances. Consider speaking to a mortgage adviser.
Why Lenders Stress-Test Affordability
Since the 2008 financial crisis, UK lenders are required by the Financial Conduct Authority (FCA) to stress-test mortgage applications. This ensures borrowers can still afford their mortgage if interest rates rise significantly.
The stress test typically adds 3% to the lender's standard variable rate (SVR) or uses a minimum rate around 7-8%. This is why you may be approved for less than you expect based on current rates alone.
What Stress Testing Means for You
- Your maximum borrowing is limited by stressed affordability, not current rates
- A comfortable stress test result means you have a financial buffer
- Failing a lender's stress test doesn't mean rates will definitely rise that high
- It protects you from taking on more debt than you can handle long-term
Today's Payment vs Future Risk
Your current monthly payment may feel comfortable, but if you're on a fixed rate that's ending soon—or already on a variable rate—you're exposed to interest rate movements. Even modest rate increases can significantly impact your budget.
Why Rates Don't Need to Reach Historic Highs
In the 1980s and 1990s, UK mortgage rates exceeded 15%. While a return to those levels is unlikely, even rates of 6-8% can cause problems for borrowers who stretched to buy at historically low rates of 2-3%.
- A £250,000 mortgage at 2% costs around £1,060/month over 25 years
- At 5%, the same mortgage costs around £1,461/month—£400 more
- At 7%, it rises to £1,767/month—over £700 more than at 2%
- This extra cost must come from somewhere in your monthly budget
How to Improve Your Stress Test Position
- Overpay your mortgage: Reducing the balance lowers future payments at any rate
- Extend your term: A longer term reduces monthly payments, though you pay more interest overall
- Reduce other debts: Lower commitments mean more income available for mortgage payments
- Build savings: An emergency fund provides a buffer if rates rise before you can adjust
- Lock in a fixed rate: Provides certainty and protection while you build financial resilience
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